For example, a laser printer performs printing on a recording medium (for example, a printing sheet) using a developer (for example, a toner). The laser printer has a case that contains the developer. The developer containing case has a case main body and a pair of rollers that are rotatably supported on the case main body. One roller is called a supply roller, and the other roller is called a developing roller. The supply roller carries the developer that is contained in the case main body. The supply roller has a rotary shaft and a cylindrical roller main body that covers the rotary shaft. The developing roller comes into contact with the supply roller outside the case main body than the supply roller does. The developing roller and the supply roller rotate while coming into contact with each other, and then the developer is supplied from the supply roller to the developing roller. At this time, the developer is positively or negatively charged by friction between the developing roller and the supply roller. The developing roller carries the positively or negatively charged developer.
The laser printer has a photosensitive member that comes into contact with the developing roller. An electrostatic latent image is formed on the surface of the photosensitive member. The developing roller and the photosensitive member rotate while coming into contact with each other, and then the developer carried on the developing roller is attached to parts of the electrostatic latent image of the photosensitive member. Accordingly, the electrostatic latent image of the photosensitive member becomes a visual image. The developer having the visual image is transferred from the photosensitive member to the recording medium, such that a letter or a drawing is printed on the recording medium.
JP-A-2002-287487 discloses a laser printer having the above-described configuration.
A developing device has a seal member that prevents developer leakage from both longitudinal ends of the developer carrier. For example, JP-A-11-190941 discloses a technique related to a developing device, a process cartridge, and an image forming apparatus that repeats a removal operation of a toner on and in an elastic roller by a scrape roller, a scrape operation of a toner stuck to a wall of a developing container by the elastic roller, and a scrape operation of the toner by the scrape member. According to this technique, an end seal member is provided at an opening of the developing container so as to seal between both ends of a developing sleeve and the developing container. The end seal member comes into contact with peripheral surfaces of both ends of the developing sleeve. Further, a side surface of the end seal member comes into contact with side surfaces of both longitudinal ends of an elastic blade, such that toner leakage from sides of the elastic blade is prevented. In addition, the scrape member is provided at a portion where the elastic blade does not come into contact with the developing sleeve and on the peripheral surfaces of both ends of the elastic roller, that is, portions where the elastic roller comes into contact with the developing sleeve.
With this configuration, the scrape member does not supply the toner from the elastic roller onto the peripheral surfaces of both ends of the developing sleeve, but scrapes the toner. Accordingly, the toner stuck onto the peripheral surfaces in the vicinity of the end seal member of the developing sleeve is made small. Therefore, it is possible to provide a developing device, a process cartridge, and an image forming apparatus that can prevent the toner from entering between the seal member and the developing sleeve.